1. Technical Field
The present invention relates to an information processing apparatus including therein a data processing unit that performs particular processing upon receiving a processing request from a processor, and especially relates to control of exceptions occurred in the data processing unit.
2. Background Art
Generally, an information processing apparatus such as a personal computer and a mobile apparatus includes therein a data processing unit, e.g. a graphics accelerator, a coprocessor, which performs predetermined processing requested by a built-in processor so as to reduce loads on the processor to increase processing efficiency thereof.
An exception might occur in processing performed by the data processing unit.
The exception indicates an abnormal situation out of a flow of a normal operation in the information processing apparatus, and includes the following situations for example: a situation where even if a processor requests the data processing unit to perform processing at a time when the data processing unit should be able to perform the processing in accordance with a program, the data processing unit cannot perform the processing; a situation where even if the processor tries to read a result of processing performed by the data processing unit at a time when the data processing unit should be able to read the result in accordance with the program, the result has not been output yet in the data processing unit; and a situation where an error occurs in the data processing unit.
In order to handle such an exception, the information processing apparatus generates an interrupt to the processor, and transfers control from a normal processing sequence to a predetermined starting address of an exception handler.
However, while the processor executes the exception handler due to the occurrence of the exception in the data processing unit, the normal processing sequence stops. Therefore, there is a demand for a technique for promptly performing switching between an exception handler and normal processing by early detecting an exception occurred in the data processing unit and a return from the exception, in order to increase processing efficiency of the processor.